Stroboscopic apparatus for calibrating time indicating devices



June 29, 148. J. M. WEINBERGER 2,444,178

STROBOSCOPIC APPARATUS FOR CALIBHATING TIME INDICATING DEVICES Filed Nov. 2, 1945 Patented June 29, 1948 STROBOSCOPIC APPARATUS FOR CALI- BRATKNG TIME INDICATING DEVICES Joseph M. Weinberger, Brooklyn, N. Y., assignor of one-half to, Tessie Weinberger, Brooklyn,

Application November 2, 1945, Serial No. 626,235

This invention relates to apparatus for call-- brating precision instruments "and more particularly to calibrating timing instruments such as clocks and watches.

This application is a continuation-impart of application Serial No. 560,686.

An object of this invention is to provide apparatus of the above mentioned character by means of which the oscillating parts of a watch or clock to be calibrated are stroboscopically compared with similar parts oi a standard watch or clock.

Another object of this invention is to provide apparatus whereby oscillations in a single direction only may be compared to those of a standard watch or clock.

A further object of this invention is to provide apparatus whereby the confusion due to observing consecutive intermittent views of the oscillating parts of the instrument to be calibrated is eliminated.

A feature of this invention resides in the manner of obstructing alternate views through the standard instrument.

Another feature resides in the construction of the obscuring disc.

Other objects and features will become apparent from the following description and the accompanying drawings in which like numerals indicate similar parts and in which:

Fig. 1 is a top view of the essential parts of one embodiment of this invention;

Fig. 2 is a diagrammatic view of the space relationships of the essential parts of this invention .at an instant when 'the slots and hole are on line and light is passing through the instrument;

Fig. 3 is a diagrammatic view of the same when an instantaneous view is obstructed;

Fig. 4 is a modified cross sectional view through the instrument on line 4-4 of Fig. 1.

The former practice in watch or clock calibration has been to compare the watch or clock to be adjusted against a mechanism which utilizes electric apparatus (such as tuning forks or piezoelectric crystals). This has been done by picking up the tick with microphones or by gauging the motion of the oscillating parts of the instrument to be calibrated with photo-electric cells. and comparing these criteria with a disc rotated by an electric motor.

Other methods in practice have been to illuminate the oscillating parts of these instruments to be v calibrated by means of electrically controlled, rapidly ionizing, gas-filled lights, during each half oscillation.

6 Claims. (GI. 88-14) These methods have proven inadequate in that these devices were inherently inaccurate, and

very expensive to manufacture.

In observing every half oscillation of the oscillating mechanism of the watch or clock to be calibrated. certain faults in the observed watch or clock produce confusion of the above mentioned criteria, resulting in misleading information toward correctly regulating the instrument.

For example, when the watch or clock to be calibrated has an oscillating mechanism which is out of beat, one half-oscillation requires more time for completion than the other. This fault is rather common in most watches, since its full correction would require more time than the results would warrant, and since a small amount of this fault would not cause serious timing errors.

However when viewed by a stroboscopic instrument. this fault produces a wavering image which is diflicult to control and too confusing for rapid adjustment.

Another difficulty is encountered when stroboscopically viewing every half-cycle of an oscillating mechanism of a watch or clock. The oscillating mechanism has an amplitude of angular motion-depending upon the condition of its gear train, pivots and other driving mechanism. Thus, when viewing every half-cycle, two distinct alternating positions of the oscillating mechanism may be seen, one for each direction of swing. These positions depend upon the instant of view and the angular speed of the observed oscillating mechanism.

When the oscillating mechanism of the instrument to be calibrated is exactly in phase with the standard instrument, these two alternating positions appear substantially stationary. However, if the phase should differ, even slightly, a wavering motion is observed in which the two positions gradually converge and diverge. The greater the. phase difference. the more frequently these two positions converge and diverge. The confusion thus created makes rapid regulation difiicult and tiring.

The present invention obviates this difllculty by obscuring alternate views of the oscillating mechanism which is being calibrated. In this manner, only a single position is seen and this position appears substantially stationary when exactly in phase with the standard instrument. A slow drift in either direction indicates an out of phase condition which can be rapidly controlled by means of proper regulation.

In its simplest embodiment, the invention comprises an oscillating balance wheel 2 having a solid disc I which is driven by a and barrel I. a gear train I and II and a lever type of cscapement comprising an escape wheel I and a lever pallet I. The balance wheel is provided with a hairspring I and roller I.

The disc of thebalance wheel 2 is provided with a slot II which passes under a corresponding slot A (11801! is II in the stationary main, plate I. attached to the shaft of the escape wheel I. This I disc I! is provided with a plurality ;of holes II uniformly spaced along the circumference of a circle about the center of rotation having a radius equal to the distance from the center of the escape wheel to the center of slot. II in the main plate I. There are as many holes in the disc-I2 as there are teeth'in the escape wheel I.

The mainspring and barrel I deliver power through the gear train I and II to the escape wheel I which in turn drives' thepallet I from side to side by applying impulses to the pallet jewels II and II. The fork II of the pallet engages the roller I producing oscillating motion of the balance wheel 2.

r A tooth II of the escape wheel is at lock against the pallet Jewel II when the balance? wheel hasv rotated away from its rest position. In this position a line of sight through slot II is obstructed by the disc I of the balance wheel I. The balance wheel returns, rotating ina direction indicated by the arrow A in Fig. 2 due to the force of the hairspring I. The roller I engages the fork II and carries it along until the jewel II unlocks tooth I1. The jewel II traverses the impulse face of the tooth I'I until the roller I is on line with the pivot of the pallet I. the staff of the balance wheel 2, and the pivot of the escape wheel I. At this instant. as shown in Fig. 2 and Fig. 4, a hole II, in the disc I2, the slot II in the balance wheel and the slot Ii in the main plate are on line. providing a line of sight through the instrument.

The balance wheel 2 completes its swing against III the force of the hairspring. The roller I carries At this instant.- as shown in Fig: 3 th slot II in the balance wheel and the slot II in the main plate are on line, but the holes II of the disc I2 straddle the line of sight with the'solid portion of the disc I2 lying across the line of sight, thus obstructing the line of sight through slots II and I In this manner a line of sight through the slots II and II is discovered only when the balance wheel is travelling in one direction, and is obscured when the balance wheel is travelling in the other direction.

The placing of the disc II on the shaftlof the escape wheel I does not'alter the timing qualities of the instrument.

The disc I2 could be placed upon anyother gear in the train provided the proper number and size of holes were chosen and the distance from the center of the disc to the centers of the holes II were made to correspond with the distance to of the pallet upon the 'escape wheel. In the present embodiment, however, it is desirable to place the disc II on the shaft of the escape wheel I.

I wish it distinctly understood that, while I have particularly described the simplest elements adapted to perform the functions set forth, it is obvious'that they could be subject to modifications, and variouschanges in form, proportion and in minor details of construction, may be resorted to without departing from the spirit or sacrificing any of the principles of the invention.

whatIclaimis:

l. A device for calibrating a time indicatingj device comprising an opaque member. means supporting said member for oscillatory motion. said oscillatory member being provided with an aperture displaced from the axis of oscillation, a second opaque member rotatably mounted adjacent said oscillatory member and provided with a plurality of uniformly spaced apertures adjacent its periphery, the relative positions of said opaque members being such that the aperture in the oscillating member mo'ves'across the'path of movement of the apertures in the rotating member, means for imparting motion to said opaque members, the spacing of said holes being so related to the rate of intermittent rotation of said rotating member and said rate being so related to the oscillatory motion of the oscillatory member that successive apertures in saidrotating member are successively aligned with the aperture in said oscillatory member in alternate half-cycles of oscillation of said oscillatory member.

2. A device for calibrating a time indicating device comprising an opaque stationary member provided with an aperture, a second opaque member adjacent said stationary member, means supporting said second member for oscillatory motion, said second member being provided with a third aperture displaced from the center of oscillation and so disposed relative to the first mentioned aperture as to be intermittently moved into alignment therewith upon motion of said second member, an opaque member rotatably mounted adjacent said oscillatory member and provided with a plurality of uniformly spaced apertures adjacent its periphery, the spacing of said apertures being so related to the rate of intermittent rotation of said rotating member and said rate being so related to the second motion of said oscillatory member that successive apertures in said third member are successively aligned with the apertures in said stationary and second members in alternate half-cycles of oscillation of said second member and means for imparting the relative motions to said second and third members.

3. A device for calibrating a time indicating device comprising an opaque stationary member providedwith an aperture, a second opaque member adjacent said stationary member, means supporting said second member for oscillatory motion, said second member being provided with an aperture displaced from th axis of oscillation and so disposed relative to the first mentioned aperture as to be intermittently moved into alignment therewith upon motion of said oscillatory member, escapement means disposed to impart motion to said oscillatory membtr. an opaque member, rotatably mounted adjacent said oscillatory member, driven by said escapement means and provided with a plurality of apertures uniformly spaced along the circumference of a circle about the center of rotation, the number and spacing of said apertures being so related to the rate of intermittent rotation of said rotating member and the "said rate being 50 related to the oscillatory motion-01' said oscillatory member that an aperture in said rotating member is aligned with the apertures in said stationary and osciila-' tory members in alternate half-cycles of oscillation of said oscillatory member. v

4. A device for calibrating a time indicating device comprising an opaque stationary member provided with an aperture, a second opaque member adjacent said stationary member, means supporting said second member for oscillatory motion, said second member being provided with an aperture displaced from the axis of oscillation and so disposed relative to the first mentioned aperture as to be intermittently moved into alignment therewith upon motionoi' said oscillatory member,escapement means comprising a wheel provided with a plurality of impulse producing teeth and a lever adapted to transfer said impulses from said wheel to said oscillatory member to impart oscillatory motion thereto, an opaque member rotatably mounted adjacent said oscillatory member, driven by said wheel and provided with a plurality of apertures uniformly spaced along the circumference oi acircle about the center of rotation. the number and spacing of said holes being so related to the number or teeth and rate of rotation of said wheel, and the said rate being so related to the oscillatory motion of said oscillatory member that an aperture in said rotating member is aligned with the apertures in said stationary and oscillatory members only in alternate hall-cycles of oscillation of said oscillatory member.

5. A device for calibrating a time indicatin device comprising an opaque stationary member provided with an aperture, a second opaque member adjacent said stationary member, means supporting said second member for oscillatory mo tion, said second member being provided with an aperture displaced from the axis of oscillation and so disposed relative to the first mentioned aperture as to be intermittently moved into alignment therewith upon motion-of said oscillatorymember, a source of rotary power, including speed reducing means and escapement means driven thereby, cooperating with said second member for imparting oscillatory motion thereto, an opaque member rotatably mounted adjacent said oscillatory member, driven by said escapement means and provided with a plurality of aperture uni- Iormly spaced adjacent its periphery, the number and spacing of said apertures being so related to the rate of intermittent rotation of said rotating member and the said rate being so related to the oscillatory motion of said second member that an aperture in said rotating member is aligned with the apertures in said first and second members only in alternate half-cycles of oscillation of said second member.

6. A device for calibrating a time indicating device comprising an opaque stationary member provided with an aperture, a second opaque member adjacent said stationary member, means supporting said second member for oscillatory motion, said second member being provided with an aperture displaced from the center of oscillation and so disposed relative to the first mentioned aperture as to be intermittently moved into alignment therewith upon motion of said oscillatory member, a source of rotary power, including speed reducing means and escapement means driven thereby, cooperating with said second member for imparting oscillatory motion thereto, an opaque member rotatably mounted adjacent said oscillatory member, driven by said escapement means and provided with a plurality of apertures uniformly spaced-adjacent its periphery, the number and spacing of said apertures being so related to the rate of intermittent rotation of said rotating member and the said rate being so related to the oscillatory motion of said second member that an aperture in said rotating member is aligned with the apertures in said first and second members only in alternate half-cycles oi oscillation of said second member, and image forming means disposed along an axis through the first mentioned aperture for viewing an object to be calibrated through the said apertures when aligned.

JOSEPH M. WEINBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,869,588 Strattner et a] Aug. 2, 1932 2,178,482 List Oct. 31, 1939 

